The term "tren" refers to a type of anabolic steroid known as trenbolone. It is commonly used in veterinary medicine to promote muscle growth in livestock. Bodybuilders and athletes sometimes misuse trenbolone for its powerful effects on muscle mass and strength, despite potential health risks. Trenbolone is known for its ability to enhance protein synthesis and nitrogen retention in the body. However, its use can lead to serious side effects, including cardiovascular issues and hormonal imbalances. Due to these risks, trenbolone is banned in competitive sports and is illegal for human use in many countries.